Anglický jazyk
2.3 Medical English - Cell and tissues
The cell
The cell is the fundamental unit of every living thing (animals, plants). Every tissue and every organ is made up of these units.
All cells are in a way similar. All contain a gelatinous substance composed of water, proteins, sugars, acids, fats, and various minerals. This substance is called protoplasm. There are bone, muscle, nerve, blood, skin cells which have specific structures in common. Each cell is divided into several compartments.
The structure that surrounds and protects the internal environment of the cell is called cell membrane. It determines what passes in and out of the cell. It has 3 layers: two made of proteins and a lipid layer in between.
The nucleus is the controlling unit of the cell. It controls the way the cell reproduces, and contains the genetic material which determines the functioning and structure of the cell. All the material in the nucleus is called nucleoplasm or karyoplasm.
The genetic material is composed of the chromosomes. These are 23 pairs of thin strands of DNA in the nucleus. The chromosomes contain genes which determine our hereditary make-up. The DNA in the chromosomes regulates the activities of each cell by guiding the formation of another substance called RNA. RNA is able to leave the nucleus, enter the cytoplasm and direct the activities of the cell.
Chromosomes differ in size, arrangement and number. This classification is called a karyotype. Karyotyping of chromosomes is useful in determining whether they are normal in number and structure.
Outside the nucleus there is cytoplasm. It carries out the work of the cell, e.g. in a muscle cell, it does the contracting, in a nerve cell, it transmits impulses.
The cytoplasm contains organelles such as mitochondria which are small bodies that product energy in the cell by burning food in the presence of oxygen. This process is called catabolism. During catabolism complex structures are broken down into simpler substances and energy is released. Then there is the endoplasmic reticulum which is a series of canals in the cell. Some canals contain small bodies called ribosomes which help make proteins for the cell. This synthesizing process is called anabolism. The processes of anabolism and catabolism together constitute the total metabolism of the cell. There are more types of small bodies in the cell, see the picture.
Cells are different = specialized throughout the body to carry out their individual functions. For example, a muscle cell is long and slender and contains fibres which help the muscle contract and relax. A skin = epithelial cell can be square and flat to provide protection. A nerve cell can be very long and have fibrous extensions which help transmit impulses. A fat cell contains large empty spaces for fat storage. There are many more types of cells in the human body.
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fundamental
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základní
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unit
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jednotka
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tissue
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tkáň
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acid
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kyselina
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fat, lipid
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tuk, tukový
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substance, matter
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látka, hmota
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compartments
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oddělení
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surround
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obklopovat
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layer
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vrstva
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determine
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určit
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strand
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pramen
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hereditary
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dědičný
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makeup
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výbava
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guide
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řídit, vést
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arrangement
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uspořádání
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carry out
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vykonávat
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contract
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stahovat
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transmit
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přenášet
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burning, combustion
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spalování
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break down
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rozkládat
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release
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uvolnit
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fibre
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vlákno
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fibrous
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vláknitý
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slender
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štíhlý
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square
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čtverec, čtvercový
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flat
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plochý
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extension
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výběžek
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space
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prostor
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storage
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zásoba, úložiště
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The tissues
Epithelial tissue lines the body internally and covers it externally. It is generally attached to a basement membrane of fibrous tissue. Internally it lines both mucous and serous membrane. Externally it overlies the dermis to form the outer layer of the skin = epidermis.
The cells of epithelial tissue are situated continuously. There is virtually no intercellular matrix. The cells can form one or more layers. Single layers are called simple, when there are more than one layers the epithelium is called stratified.
There are various types of simple epithelium, classified mainly according to cell shape. Simple epithelium with flattened cells lying edge to edge is called pavement epithelium. It makes the smooth surface lining the serous membranes of the pleura, pericardium and peritoneum. It is also found wherever a very thin membrane is required, e.g. in the terminal vesicles of the renal tubules.
Columnar epithelium contains column-shaped cells. These lie edge to edge, too. Columnar epithelium lines the mucous membrane of the stomach and the intestines. It also lines the gallbladder and bile ducts, and the ducts of several glands. The height of the columnar cells varies from region to region. In some parts of the body such as inside the convoluted portions of the renal tubules, the cells are so low that their height equals their width. The epithelium is then called cubical epithelium. In other regions a protoplasmic hair might be attached to each columnar cell. These hairs are known as cilia and the epithelium is referred to as columnar ciliated epithelium. It is found in many parts of the body, but most notably in the nasal cavities.
The most important stratified epithelium is stratified squamous epithelium which forms the epidermis. As its cells approach the surface they gradually lose their protoplasmic contents and become flatter and more scale-like = squamous. At the same time the cells in the superficial layers are gradually converted into keratin, especially in the palmar and plantar regions. Stratified squamous epithelium also lined the oral cavity, the lower part of larynx, the oesophagus, the anal canal and vagina. In these areas there is little keratin and the epithelium is not so thick.
Other types of stratified epithelium are found. For example, there is a deep layer of conical and oval cells under the epithelium that lines the mucous membrane of the trachea and the bronchi.
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line, cover
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pokrývat
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attach
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přiložit, připevnit
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basement
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základ
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overlie
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překrývat
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outer X inner
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vnější X vnitřní
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virtually
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v podstatě
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intercellular matrix
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mezibuněčná hmota
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main
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hlavní
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according to
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podle čeho
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pavement epithelium
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dlaždicovitý epitel
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flatten
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zploštit
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edge
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okraj
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smooth
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hladký
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surface
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povrch
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wherever
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kdekoli
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require
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požadovat, vyžadovat
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terminal
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konečný
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renal tubules
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renální tubuly
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column
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sloup, sloupec
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column-shaped
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sloupcovitý
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bile duct
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žlučovod
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gland
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uzlina, žláza
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convoluted
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zatočený, zahnutý, pokroucený
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height
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výška
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width
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šířka
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nasal cavity
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nosní dutina
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gradual
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postupný
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scale-like
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šupinovitý, vypadající jako šupina
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superficial
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povrchový
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convert in/into
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přeměnit na
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palmar region
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oblast dlaně
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plantar region
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oblast chodidla
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connective tissue (obr.)
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vazivo
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